Methods for producing ceramic substrates and module components

ABSTRACT

In a method for manufacturing ceramic substrates and module components, an unfired mother ceramic substrate is cut at predetermined positions for division into separate unfired ceramic substrates. The cut unfired mother ceramic substrate is pressed such that pressure is applied parallel or substantially parallel to its main surfaces so that the cross-sectional end surfaces created in the cutting step are joined. The unfired mother ceramic substrate including end surface junctions, resulting from joining of the cross-sectional end surfaces, is fired. The fired mother ceramic substrate is broken along the end surface junctions to divide it into separate ceramic substrates.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication 2014-0038617 filed Feb. 28, 2014 and is a ContinuationApplication of PCT/JP2015/051353 filed on Jan. 20, 2015. The entirecontents of each application are hereby incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to methods for the production of ceramicsubstrates and module components and specifically to methods for theproduction of ceramic substrates and module components that are producedthrough a step of dividing a mother ceramic substrate into separatesubstrates.

2. Description of the Related Art

In the production of ceramic substrates, methods in which a fired motherceramic substrate is divided into separate ceramic substrates arecommonly used.

As a method for dividing a fired mother substrate into separate ceramicsubstrates of a predetermined size, for example, Japanese UnexaminedPatent Application Publication No. 2005-15293 discloses a method inwhich a sintered ferrite substrate, which is a sintered ferrite plate(ceramic plate) with a layer of adhesive material on one surface, is cutwith at least one continuous notch to provide a sintered ferritesubstrate that can be divided starting from this continuous notch, andthis is divided into separate ceramic substrates.

Japanese Unexamined Patent Application Publication No. 2007-165540discloses a method for producing multilayer ceramic substrates in whicha multilayer body that is a stack of multiple substrate green sheets,with an anti-shrinkage green sheet on each side thereof and at least oneof the anti-shrinkage green sheets having a notch pattern on its surfaceas a guide for the formation of a notch for division, is cut with anotch for the division of the substrate in its surface using the notchpattern on the anti-shrinkage green sheet, fired, and then divided alongthe notch.

The methods disclosed in Japanese Unexamined Patent ApplicationPublication No. 2005-15293 and Japanese Unexamined Patent ApplicationPublication No. 2007-165540, however, need to be further improved. Inthese methods, as illustrated in FIGS. 20A and 20B, notches 201 forbreaking are formed in one surface 200 a of a mother substrate 200, andthe mother substrate 200 is broken starting from these notches. Thisconfiguration makes it difficult to divide the mother substrate 200while creating end surfaces 202 perpendicular to the surface 200 a ofthe mother substrate 200 as intended, occasionally causing the endsurfaces 202 to be angled as schematically illustrated in FIG. 21.

Furthermore, the methods disclosed in Japanese Unexamined PatentApplication Publication No. 2005-15293 and Japanese Unexamined PatentApplication Publication No. 2007-165540 are of poor productionefficiency. When notches are formed in multiple mother substrates inthese methods, in which notches 201 from which breaking starts areformed in a surface 200 a of a mother substrate 200 as illustrated inFIGS. 20A and 20B, the notches 201 need to be formed in each of themother substrates 200.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide methods for theproduction of ceramic substrates and module components that make itpossible to divide a mother ceramic substrate while creating endsurfaces perpendicular or substantially perpendicular to the surface ofthe mother ceramic substrate. These methods allow for efficientproduction of ceramic substrates with high form accuracy and modulecomponents composed of these ceramic substrates and surface mountdevices thereon.

A method according to a preferred embodiment of the present inventionfor producing ceramic substrates is a method for producing ceramicsubstrates that are produced through a step of dividing a mother ceramicsubstrate at a predetermined position into a plurality of ceramicsubstrates. The method includes a cutting step in which an unfiredmother ceramic substrate that has yet to be fired is cut at apredetermined position from one main surface through to the other mainsurface to divide the unfired mother ceramic substrate into separateunfired ceramic substrates; a pressing step in which the cut unfiredmother ceramic substrate is pressed to apply pressure in the directionparallel or substantially parallel to the main surfaces thereof so thatthe cross-sectional end surfaces created in the cutting step are joined,combining the separate ceramic substrates into a single unit; a firingstep in which the unfired mother ceramic substrate including an endsurface junction, an area resulting from joining the cross-sectional endsurfaces, is fired; and a dividing step in which the fired motherceramic substrate is broken along the end surface junction to divide themother ceramic substrate into separate ceramic substrates.

In a method according to a preferred embodiment of the present inventionfor producing ceramic substrates, the unfired mother ceramic substratemay have a multilayer structure formed by stacking a plurality ofceramic green sheets, and the ceramic substrates obtained by dividingthe fired mother ceramic substrate in the dividing step may bemultilayer ceramic substrates.

This configuration allows for efficient production of multilayer ceramicsubstrates, which have a structure in which multiple ceramic layers arestacked.

It is preferred that a stack of unfired mother ceramic substrates with aresin layer therebetween that disappears in the firing step go throughthe cutting and pressing steps and the firing step, in which the resinlayer disappears, and then be subjected to the dividing step.

This configuration, in which a stack of a predetermined number ofunfired mother ceramic substrates is subjected to the steps from cuttingto firing, allows for efficient production of ceramic substrates(multiple ceramic substrates including single-layer and multilayerceramic substrates).

In a method according to a preferred embodiment of the present inventionfor producing ceramic substrates, the unfired mother ceramicsubstrate(s) may include a conductor pattern made of a material thatbecomes a metallic conductor through firing so that the cutting,pressing, firing, and dividing steps provide ceramic substratescontaining a metallic conductor.

This configuration allows for efficient production of ceramic substratesthat contain conductors, such as circuits and electrodes.

A method according to a preferred embodiment of the present inventionfor producing module components is a method for producing modulecomponents that are produced through a step of dividing a mother ceramicsubstrate with surface mount devices thereon at a predetermined positioninto a plurality of separate ceramic substrates. The method preferablyincludes a cutting step in which an unfired mother ceramic substratethat has yet to be fired is cut at a predetermined position from onemain surface through to the other main surface to divide the unfiredmother ceramic substrate into separate unfired ceramic substrates; apressing step in which the cut unfired mother ceramic substrate ispressed to apply pressure in the direction parallel or substantiallyparallel to the main surfaces thereof so that the cross-sectional endsurfaces created in the cutting step are joined, combining the separateceramic substrates into a single unit; a firing step in which theunfired mother ceramic substrate including an end surface junction, anarea resulting from joining the cross-sectional end surfaces, is fired;a device-mounting step in which a surface mount device is mounted toeach of the ceramic substrates in the fired mother ceramic substrate;and a dividing step in which the fired mother ceramic substrate, withthe surface mount device on each of the ceramic substrates, is brokenalong the end surface junction to divide the mother ceramic substrateinto separate module components each composed of each of the ceramicsubstrates and the surface mount device thereon.

In a method according to a preferred embodiment of the present inventionfor producing module components, the unfired mother ceramic substratemay have a multilayer structure formed by stacking a plurality ofceramic green sheets, and the ceramic substrates as a structural elementof the module components obtained by dividing the fired mother ceramicsubstrate in the dividing step may be multilayer ceramic substrates.

This configuration allows for efficient production of module componentseach composed of a multilayer ceramic substrate, which has a structurein which multiple ceramic layers are stacked, and a surface mount devicethereon.

It is preferred that a stack of unfired mother ceramic substrates with aresin layer therebetween that disappears in the firing step go throughthe cutting and pressing steps and the firing step, in which the resinlayer disappears, and then each of the fired mother ceramic substratesbe subjected to the device-mounting and dividing steps.

This configuration, in which a stack of a predetermined number ofunfired mother ceramic substrates is subjected to the steps from cuttingto firing, allows for efficient production of module components eachcomposed of a single-layer or multilayer ceramic substrate and a surfacemount device thereon.

It is desirable that the unfired mother ceramic substrate(s) contain aconductor pattern made of a material that becomes a metallic conductorthrough firing so that the cutting, pressing, firing, device-mounting,and dividing steps provide separate module components each composed of aceramic substrate containing a metallic conductor and the surface mountdevice on the ceramic substrate.

This configuration allows for efficient production of module componentseach composed of a ceramic substrate and a surface mount device thereonwith conductors, such as circuits and electrodes, in the ceramicsubstrate.

As described above, a method according to a preferred embodiment of thepresent invention for producing ceramic substrates includes a cuttingstep in which an unfired mother ceramic substrate is cut from one mainsurface through to the other main surface to divide it into separateunfired ceramic substrates, a pressing step in which the cut unfiredmother ceramic substrate is pressed to join the cross-sectional endsurfaces created in the cutting step to combine the separate ceramicsubstrates into a single unit, a firing step in which the unfired motherceramic substrate including an end surface junction, an area resultingfrom joining the cross-sectional end surfaces, is fired, and a dividingstep in which the fired mother ceramic substrate is broken along the endsurface junction to divide it into separate ceramic substrates. Thismethod, in which a fired mother ceramic substrate is broken along theend surface junction, ensures that the mother ceramic substrate isbroken at a predetermined position, thus allowing the manufacturer toproduce ceramic substrates having an intended shape with highefficiency.

The ceramic materials of which the ceramic substrates according tovarious preferred embodiments of the present invention can be madeinclude a variety of ceramic materials such as magnetic ceramics,dielectric ceramics, piezoelectric ceramics, and semiconductor ceramics.

The ceramic substrates as used in various preferred embodiments of thepresent invention are not limited to what are called circuit boards,which are substrates that have circuits and related elements on theirsurface and/or inside them. Preferred embodiments of the presentinvention can also be applied when flat-plate ceramic articles areproduced with no circuit conductors or other elements provided.

A method according to a preferred embodiment of the present inventionfor producing module components includes a cutting step in which anunfired mother ceramic substrate is cut from one main surface through tothe other main surface to divide it into separate unfired ceramicsubstrates, a pressing step in which the cut unfired mother ceramicsubstrate is pressed to join the cross-sectional end surfaces created inthe cutting step to combine the separate ceramic substrates into asingle unit, a firing step in which the unfired mother ceramic substrateincluding an end surface junction, an area resulting from joining thecross-sectional end surfaces, is fired, a device-mounting step in whichsurface mount devices are mounted to the fired mother ceramic substrate,and a dividing step in which the fired mother ceramic substrate isbroken along the end surface junction to divide it into separate modulecomponents. This method, in which a fired mother ceramic substrate isbroken along the end surface junction, ensures that the mother ceramicsubstrate is broken at a predetermined position, thus allowing themanufacturer to produce with high efficiency module components eachcomposed of a ceramic substrate in an intended shape and a surface mountdevice thereon.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a front view of an unfired mother ceramic substrate used inan preferred embodiment (Preferred Embodiment 1) of the presentinvention. FIG. 1B is a plan view of the same.

FIG. 2A is a front view of a cut unfired mother ceramic substrate inPreferred Embodiment 1 of the present invention. FIG. 2B is a plan viewof the same.

FIG. 3 is a front view of the cut unfired mother ceramic substrate inPreferred Embodiment 1 of the present invention that had been pressed tojoin the cross-sectional end surfaces created in the cutting step.

FIG. 4 is a front view of the unfired mother ceramic substrate that hadbeen fired with its cross-sectional end surfaces joined.

FIG. 5 is a front view of the fired mother ceramic substrate that hadbeen divided into separate ceramic substrates.

FIG. 6 is a front view of an unfired composite multilayer body formed bystacking five multilayer bodies with a resin layer therebetween, each ofthe multilayer bodies being a stack of ceramic green sheets, inPreferred Embodiment 2 of the present invention.

FIG. 7 is a front view of the unfired composite multilayer body in FIG.6 that had been cut.

FIG. 8 is a front view of the cut unfired composite multilayer body inFIG. 7 that had been pressed (isostatically pressed) to join thecross-sectional end surfaces created in the cutting step.

FIG. 9 is a front view of the separate mother ceramic substratesobtained after firing a composite multilayer body in whichcross-sectional end surfaces have been joined in a pressing step.

FIG. 10 is a schematic front view of the fired mother ceramic substratesthat had been divided into separate ceramic substrates.

FIG. 11 is a front view of a variation of Preferred Embodiment 2 of thepresent invention.

FIG. 12 is a perspective view of the structure of a module componentproduced using a method according to Preferred Embodiment 3 for theproduction of module components.

FIG. 13 is a perspective view of a patterned sheet in PreferredEmbodiment 3 of the present invention, which was a ceramic green sheetwith a conductor pattern placed thereon.

FIG. 14 is a perspective view of patterned sheets of FIG. 13 stacked ina predetermined order.

FIG. 15 is a perspective view of a multilayer body (an unfired motherceramic substrate) obtained by pressure-bonding a stack of patternedsheets of FIG. 13.

FIG. 16 is a perspective view of the multilayer body (unfired motherceramic substrate) in FIG. 15 that had been cut.

FIG. 17 is a perspective view of the cut unfired multilayer body(unfired mother ceramic substrate) in FIG. 16 that had been pressed(isostatically pressed) to join the cross-sectional end surfaces createdin the cutting step.

FIG. 18 is a perspective view of the mother ceramic substrate in FIG. 17that had been fired with its cross-sectional end surfaces joined and towhich surface mount devices had been mounted.

FIG. 19 is a schematic perspective view of the fired mother ceramicsubstrate that had been broken and divided into separate modulecomponents.

FIG. 20A is a front view of a known method for dividing a mothersubstrate. FIG. 20B is a top view of the same.

FIG. 21 is a diagram that illustrates a problem with the known methodfor dividing a mother substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following describes preferred embodiments of the present invention.

Preferred Embodiment 1

Preferred Embodiment 1 provides a method in which ceramic substrates(multilayer ceramic substrates) of a magnetic ceramic material wereproduced.

A magnetic ceramic powder (a ferrite powder in Preferred Embodiment 1),a binder resin, and an organic solvent were mixed. After dissolution anddispersion, defoaming was performed to provide a starting ceramicslurry.

(1) The prepared starting ceramic slurry was applied to 50-μm-thick PETfilms (supporting films) and dried using known methods, such as doctorblading, to provide 50-μm-thick ceramic green sheets.

(2) The ceramic green sheets were punched to make 200 mm×200 mm pieces.The ceramic green sheet of each removed piece was separated from the PETfilm.

Four separated ceramic green sheets were stacked to provide a multilayerbody having dimensions in plan view of 200 mm×200 mm and a thickness of0.2 mm.

Each of the stacked ceramic green sheets may include thereon a surfaceconductor pattern that provides surface conductors, an inner conductorpattern that provides inner conductors, and via conductors that providesinterlayer coupling.

(3) After degassing in a bag, the multilayer body was tightly sealed andheated to a predetermined temperature. Isostatic pressing was thenperformed at 20 MPa for 1 minute. This provided an unfired motherceramic substrate 10 that was a pressure-bonded stack of four ceramicgreen sheets 1 as illustrated in FIGS. 1A and 1B.

(4) The unfired mother ceramic substrate 10 was cut at 2.44-mm intervalsby push-cutting using a 0.10-mm-thick cutting blade 30 on an adhesiveholding sheet 20 as illustrated in FIGS. 2A and 2B.

In this process of cutting the unfired mother ceramic substrate 10, thecutting blade 30 was infiltrated until its edge reached the adhesiveholding sheet 20, i.e., from one main surface 10 a of the unfired motherceramic substrate 10 to the other main surface 10 b.

The end surfaces 10 c created through cutting (cross-sectional endsurfaces) are perpendicular or substantially perpendicular to the mainsurfaces 10 a and 10 b of the unfired mother ceramic substrate 10.

While being cut, the unfired mother ceramic substrate 10 is stuck on theadhesive holding sheet 20. This ensures that the unfired mother ceramicsubstrate 10 is cut into completely separate pieces, but the cut pieces(individual pieces that are to be fired into ceramic substrates) 11 a(FIGS. 2A and 2B) are held in the same positions as before cutting anddo not break up.

(5) After degassing in a bag, the cut unfired mother ceramic substrate10 was tightly sealed and heated to a predetermined temperature.Isostatic pressing was then performed at 100 MPa for 1 minute. In thisstep of isostatic pressing, the unfired mother ceramic substrate 10 ispressed such that pressure is applied not only in the directionperpendicular or substantially perpendicular to its main surfaces 10 aand 10 b but also in the direction parallel or substantially parallel toits main surfaces 10 a and 10 b. This provides an unfired mother ceramicsubstrate 10X that includes end surface junctions 10 d, areas resultingfrom joining the end surfaces 10 c created through cutting(cross-sectional end surfaces) (a joint unfired mother ceramic substrateexisting as a whole unit as a result of the joining of thecross-sectional end surfaces 10 c) (FIG. 3).

(6) The margins of the joint unfired mother ceramic substrate 10X arecut away to provide a 180 mm×180 mm joint body.

The unfired mother ceramic substrate illustrated in FIGS. 1 to 3 doesnot include the margins to be cut away.

(7) After removal of the adhesive holding sheet 20 from the joint body(joint unfired mother ceramic substrate) 10X, firing was performed at950° C. for 2 hours to provide a sintered mother ceramic substrate 10Y(FIG. 4).

The end surfaces (cross-sectional end surfaces) 10 c are still joined atthis stage, holding the whole sintered mother ceramic substrate 10Ytogether as a single unit.

The sintered mother ceramic substrate 10Y has dimensions in plan view of150 mm×150 mm and a thickness of 150 μm. The mother ceramic substratealso has areas 10 d formed in the longitudinal and lateral directions at2-mm intervals as a result of joining the cross-sectional end surfaces10 c (FIG. 3) and where the substrate is weaker than in the other areasand is to be divided (end surface junctions).

(8) The sintered mother ceramic substrate 10Y was broken on a10-μm-thick adhesive PET film (not illustrated) using a roller breakerto divide the sintered mother ceramic substrate 10Y into separatesintered ceramic substrates 11. As a result, the sintered mother ceramicsubstrate 10Y was divided along the end surface junctions 10 d asillustrated in FIG. 5, and ceramic substrates (multilayer ceramicsubstrates) 11 were obtained with their end surfaces 11 c resulting fromdivision perpendicular or substantially perpendicular to their mainsurface 12 a and therefore with high dimensional and form accuracy.

In this method according to Preferred Embodiment 1, end surfacejunctions 10 d, which are areas resulting from joining end surfaces(cross-sectional end surfaces) and weaker than the other areas, providesplanes for division. The mother substrate is broken to create the endsurfaces (planes resulting from division) 11 c of the resulting ceramicsubstrates 11 along the end surface junctions 10 d as a guide. As aresult, the ceramic substrates (multilayer ceramic substrates) 11 areobtained with the end surfaces 11 c resulting from divisionperpendicular or substantially perpendicular to their main surface 12 a,not angled.

Preferred Embodiment 2

Preferred Embodiment 2 provides a method for the production of ceramicsubstrates in which the ceramic substrates are produced more efficientlythan in Preferred Embodiment 1.

(1) Ceramic green sheets identical to those prepared in PreferredEmbodiment 1 were prepared in the same way in Preferred Embodiment 1.

In Preferred Embodiment 2, too, each of the ceramic green sheets mayinclude thereon a surface conductor pattern that provides surfaceconductors, an inner conductor pattern that provides inner conductors,and via conductors that provide interlayer coupling.

The ceramic green sheets were punched to make a 200 mm×200 mm hole. Fourceramic green sheets separated from the PET films were piled up toprovide a multilayer body identical to that prepared in PreferredEmbodiment 1, i.e., a multilayer body having dimensions in plan view of200 mm×200 mm and a thickness of 0.2 mm.

(2) As illustrated in FIG. 6, five multilayer bodies (separate unfiredmother ceramic substrates) 10 were stacked with 10-μm-thick resin layers21 therebetween to form a composite multilayer body (unfired compositemultilayer body) 110.

More specifically, the top surface of one multilayer body 10 is coatedwith a resin paste that burns away when heated in the subsequent firingstep, forming a resin layer 21. A multilayer body 10 having dimensionsin plan view of 200 mm×200 mm and a thickness of 0.2 mm was placed onthe resin layer 21. This was repeated to form the unfired compositemultilayer body 110 as a stack of five multilayer bodies 10. Instead ofthe resin paste, the resin layers 21 may be resin sheets that burn awaywhen heated in the firing step.

(3) After degassing in a bag, the unfired composite multilayer body 110was tightly sealed and heated to a predetermined temperature. Isostaticpressing was then performed at 20 MPa for 1 minute.

(4) The pressed unfired composite multilayer body 110 was cut at 2.44-mmintervals by push-cutting using a 0.10-mm-thick cutting blade 30 on anadhesive holding sheet 20 as illustrated in FIG. 7.

In this process of cutting the unfired composite multilayer body 110,the cutting blade 30 was infiltrated until its edge reached the adhesiveholding sheet 20, i.e., from one main surface 110 a of the unfiredcomposite multilayer body 110 to the other main surface 110 b.

The end surfaces 110 c (10 c) created through cutting (cross-sectionalend surfaces) are perpendicular or substantially perpendicular to themain surfaces 110 a and 110 b of the unfired composite multilayer body110.

While being cut, the unfired composite multilayer body 110 is stuck onthe adhesive holding sheet 20. This ensures that the cut multilayerpieces 111 a are held in the same positions as before cutting and do notbreak up.

(5) After degassing in a bag, the cut unfired composite multilayer body110 was tightly sealed and heated to a predetermined temperature.Isostatic pressing was then performed at 100 MPa for 1 minute. In thisstep of isostatic pressing, the unfired composite multilayer body 110 isisostatically pressed such that pressure is applied not only in thedirection perpendicular or substantially perpendicular to its mainsurfaces 110 a and 110 b but also in the direction parallel orsubstantially parallel to its main surfaces 110 a and 110 b. Thisprovides a joint body (joint unfired composite multilayer body) 110Xthat exists as a whole unit again as a result of the joining of the endsurfaces created through cutting (cross-sectional end surfaces) 110 c(10 c) as illustrated in FIG. 8.

(6) The margins of the joint body (joint unfired composite multilayerbody) 110X are cut away to provide a 180 mm×180 mm joint body.

The unfired composite multilayer body illustrated in FIGS. 6 to 8 doesnot include the margins to be cut away.

(7) After removal of the adhesive holding sheet 20 from the joint body(joint unfired composite multilayer body) 110X, firing was performed at950° C. for 2 hours. The resin layers 21 burn away, giving sinteredmother ceramic substrates 10Y (FIG. 9), separate mother ceramicsubstrates released from the resin layers 21 that have bonded themtogether (FIG. 8).

In the sintered mother ceramic substrates 10Y at this stage thecross-sectional end surfaces 10 c are still joined, holding the wholesintered mother ceramic substrate 10Y together as a single unit.

Each of the sintered mother ceramic substrates 10Y has dimensions inplan view of 150 mm×150 mm and a thickness of 150 μm. The mother ceramicsubstrate also has areas 10 d formed in the longitudinal and lateraldirections at 2-mm intervals as a result of joining the end surfaces(cross-sectional end surfaces) 10 c and where the substrate is weakerthan in the other areas and is to be divided (end surface junctions).

(8) Each sintered mother ceramic substrate 10Y was broken on a10-μm-thick adhesive PET film (not illustrated) using a roller breakerto divide the mother ceramic substrate 10Y into separate sinteredceramic substrates 11 (see FIG. 10). As a result, each sintered motherceramic substrate 10Y was divided along the end surface junctions 10 d,and ceramic substrates (multilayer ceramic substrates) 11 were obtainedwith their end surfaces 11 c resulting from division perpendicular orsubstantially perpendicular to their main surface 12 a and thereforewith high dimensional and form accuracy.

In this method according to Preferred Embodiment 2, the (4) cuttingstep, the (5) pressing step for joining end surfaces, and the (7) firingstep can be performed with multiple mother ceramic substrates stackedinto a composite multilayer body. This method therefore allows forefficient production of ceramic substrates (multilayer ceramicsubstrates) with high dimensional and form accuracy.

Variation of Preferred Embodiment 2

In Preferred Embodiment 2, four ceramic green sheets were piled up intoa multilayer body (unfired mother ceramic substrate) 10, and fivemultilayer bodies 10 were stacked with resin layers 21 therebetween toform a composite multilayer body (unfired composite multilayer body)110. Alternatively, five single-layer ceramic green sheets 1 may bestacked with resin layers 21 therebetween to form a composite multilayerbody (unfired composite multilayer body) 110 that has four resin layers21 and five single-layer ceramic green sheets 1 as illustrated in FIG.11.

Single-layer ceramic substrates can be efficiently produced by repeatingthe same steps as in Preferred Embodiment 2 except that the formation ofthe composite multilayer body (unfired composite multilayer body) 110 isas described above. No detailed descriptions or drawings are given forthe steps other than the step of forming the composite multilayer body(unfired composite multilayer body) 110, which are the same as inPreferred Embodiment 2.

In this variation of Preferred Embodiment 2, too, the ceramic greensheets may have a surface conductor pattern formed thereon that providessurface conductors or alternatively have no such element.

In this method, as in Preferred Embodiment 2, all steps can be performedwith multiple ceramic green sheets stacked into a composite multilayerbody. This method therefore allows for efficient production of ceramicsubstrates (ceramic articles) with high dimensional and form accuracy.

Preferred Embodiment 3

Preferred Embodiment 3 provides a method for the production of modulecomponents 150 that each include a multilayer ceramic substrate 11including elements such as surface conductors, inner conductors, and viaconductors and surface mount devices 151 on the multilayer ceramicsubstrate 11 as illustrated in FIG. 12.

(1) Ceramic green sheets 1 are prepared in the same way as in PreferredEmbodiment 1. The resulting ceramic green sheets are subjected to someoperations, e.g., the formation of conductor patterns that providesurface conductors and inner conductors, the formation of via holes, andthe filling of the via holes with a conductor material that forms viaconductors, to provide patterned sheets 101 a that each have necessaryconductor patterns 140 as illustrated in FIG. 13.

(2) The patterned sheets 101 a with conductor patterns 140 are stackedin a predetermined order (FIG. 14). After degassing in a bag, themultilayer body was tightly sealed, heated to a predeterminedtemperature, and isostatically pressed to provide a multilayer body(unfired mother ceramic substrate) 10 that was a pressure-bonded stackof the patterned sheets 101 a as illustrated in FIG. 15.

(3) The unfired mother ceramic substrate 10 was cut at predeterminedintervals by push-cutting using a 0.10-mm-thick cutting blade (notillustrated) on an adhesive holding sheet 20 as illustrated in FIG. 16.

In this process of cutting the unfired mother ceramic substrate 10, thecutting blade was infiltrated until its edge reached the adhesiveholding sheet 20, i.e., from one main surface 10 a of the unfired motherceramic substrate 10 to the other main surface 10 b.

The end surfaces 10 c created through cutting (cross-sectional endsurfaces) are perpendicular or substantially perpendicular to the mainsurfaces 10 a and 10 b of the unfired mother ceramic substrate 10.

While being cut, the unfired mother ceramic substrate 10 is stuck on theadhesive holding sheet 20. This ensures that the cut pieces (individualpieces that are to be fired into ceramic substrates (unfired ceramicsubstrates)) 11 a (FIG. 16) are held in the same positions as beforecutting and do not break up.

(4) After degassing in a bag, the cut unfired mother ceramic substrate10 was tightly sealed and heated to a predetermined temperature.Isostatic pressing was then performed at 100 MPa for 1 minute. In thisstep of isostatic pressing, the unfired mother ceramic substrate 10 isisostatically pressed in such a manner that pressure is applied in thedirection parallel or substantially parallel to its main surfaces 10 aand 10 b. This provides an unfired mother ceramic substrate 10X thatincludes end surface junctions 10 d, areas resulting from joining theend surfaces 10 c created through cutting (cross-sectional end surfaces)(a joint unfired mother ceramic substrate existing as a whole unit as aresult of the joining of the cross-sectional end surfaces 10 c) (FIG.17).

(5) The margins of the joint unfired mother ceramic substrate 10X arecut away to provide a 180 mm×180 mm joint body.

The unfired mother ceramic substrate illustrated in FIGS. 13 to 17 doesnot include the margins to be cut away.

(6) After removal of the adhesive holding sheet 20 from the jointunfired mother ceramic substrate 10X, firing was performed at 950° C.for 2 hours to provide a sintered mother ceramic substrate 10Y (FIG.18).

The end surfaces (cross-sectional end surfaces) 10 c are still joined atthis stage, holding the whole sintered mother ceramic substrate 10Ytogether as a single unit.

The sintered mother ceramic substrate 10Y at this stage includes areas10 d that have resulted from joining the cross-sectional end surfaces 10c (FIG. 16) and where the substrate is weaker than in the other areasand is to be divided (end surface junctions).

(7) Each of the surface mount devices 151 was mounted to each of thepieces (ceramic substrates) 11, which are to be fired into ceramicsubstrates, of the sintered mother ceramic substrate 10Y (FIG. 18).

The surface mount devices 151 mounted are, for example, IC chips,multilayer ceramic capacitors, chip inductors, and chip resistors.

(8) The mother ceramic substrate 10Y with surface mount devices 151 oneach ceramic substrate was broken along the end surface junctions 10 d(FIG. 19). This provides module components 150 each including a ceramicsubstrate (multilayer ceramic substrate) 11 and surface mount devices151 thereon with their end surfaces 11 c resulting from divisionperpendicular or substantially perpendicular to their main surface 12 aand therefore with high dimensional and form accuracy.

In this method according to Preferred Embodiment 3, all steps includingthe cutting, pressing, firing, and mounting steps can together beperformed with ceramic substrates in assembly. This method thereforeallows for efficient production of module components each including aceramic substrate and surface mount devices thereon with highdimensional and form accuracy.

Although multilayer ceramic substrates are described as examples inPreferred Embodiments 1 and 2, the present invention is also applicableto the production of single-layer ceramic substrates.

Although module components each including a multilayer ceramic substrateand surface mount electronic devices thereon are described as examplesin Preferred Embodiment 3, the present invention is also applicable tothe production of module components each including a single-layerceramic substrate and surface mount electronic devices thereon.

In all other respects, too, the present invention is not limited to theabove preferred embodiments. Various applications and modificationswithin the scope of the present invention can be made to conditions suchas the dimensions and shape of the ceramic substrates to be produced andthe production process including the cutting method used when cuttingthe unfired mother ceramic substrate and the equipment for this, thepressing method used in the pressing step, and the method used to breakthe sintered mother ceramic substrate.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A method for producing ceramic substrates thatare produced by dividing a mother ceramic substrate at a predeterminedposition into a plurality of ceramic substrates, the method comprising:cutting an unfired mother ceramic substrate that has yet to be fired ata predetermined position from one main surface through to the other mainsurface to divide the unfired mother ceramic substrate into separateunfired ceramic substrates; pressing the separate unfired mother ceramicsubstrates to apply pressure in a direction parallel or substantiallyparallel to the main surfaces thereof so that cross-sectional endsurfaces created in the cutting are joined, combining the separateunfired ceramic substrates into a pressed unfired mother ceramicsubstrate that is a single unit and includes an end surface junctionwhich is an area resulting from joining the cross-sectional endsurfaces; firing the pressed unfired mother ceramic substrate to form afired mother ceramic substrate; and dividing the fired mother ceramicsubstrate by breaking the fired mother ceramic substrate along the endsurface junction to divide the fired mother ceramic substrate intoseparate fired ceramic substrates.
 2. The method according to claim 1,wherein the unfired mother ceramic substrate has a multilayer structureformed by stacking a plurality of ceramic green sheets, and the separatefired ceramic substrates obtained by dividing the fired mother ceramicsubstrate are multilayer ceramic substrates.
 3. The method according toclaim 2, further comprising forming at least one of a surface conductoron at least one of the plurality of ceramic green sheets, an innerconductor pattern on at least one of the plurality of ceramic greensheets, and a via conductor in at least one of the plurality of ceramicgreen sheets.
 4. The method according to claim 1, wherein the unfiredmother ceramic substrate includes a conductor pattern made of a materialthat becomes a metallic conductor through firing so that the cutting,pressing, firing, and dividing provide ceramic substrates including ametallic conductor.
 5. The method according to claim 1, furthercomprising forming the mother ceramic substrate of a magnetic ceramicmaterial.
 6. The method according to claim 1, wherein the unfired motherceramic substrate that has yet to be fired is an unfired multilayer bodyformed by stacking unfired mother ceramic substrates with a resin layertherebetween, and the unfired multilayer body goes through the cutting,the pressing, and the firing, in which the resin layer burns away, andthen the multilayer body is subjected to the dividing.
 7. The methodaccording to claim 1, wherein the cutting includes formingcross-sectional end surfaces that are perpendicular or substantiallyperpendicular to the main surfaces of the unfired mother ceramicsubstrate.
 8. The method according to claim 1, wherein the cuttingincludes sticking the unfired mother ceramic substrate on an adhesiveholding sheet.
 9. The method according to claim 1, wherein the pressingfurther includes pressing the separate unfired mother ceramic substratesto apply pressure in a direction perpendicular or substantiallyperpendicular to the main surfaces thereof.